A. Field of the Invention
This invention relates to a process for the manufacture of dicarboxylic acid anhydrides by the oxidation of hydrocarbons. More particularly, it is directed to a process suitable for producing maleic anhydride from saturated hydrocarbons in higher yields than heretofore possible.
B. The Prior Art
Maleic anhydride is of significant commercial interest throughout the world. It is used alone or in combination with other acids in the manufacture of alkyd and polyester resins. It is also a versatile intermediate for chemical synthesis. Significant quantities of maleic anhydride are produced each year to satisfy these needs. The prior art discloses a number of processes used in the conversion of organic feedstocks to maleic anhydride.
Of particular interest is U.S. Pat. No. 3,293,268 which teaches a process of oxidizing saturated aliphatic hydrocarbons to maleic anhydride under controlled temperature conditions and in the presence of phosphorus-vanadium-oxygen catalysts. Through various improvements including the use of promoters such as cobalt, nickel, cadmium and titanium yields have been substantially increased, as exemplified in U.S. Pat. No. 4,111,963, U.S. Pat. No. 3,987,063, and U.S. Pat. No. 3,907,833.
Any economically feasible method of substantially reducing the operating temperature or increasing the level of selectivity in the manufacture of maleic anhydride including alternative methods to those already known could be a substantial advance in the art and is an object of this invention.